The invention relates to the field of training devices and simulators, and, more specifically, to training in the use and wearing of a supplemental air supply apparatus that involves a face mask and an oxygen source. In particular, the invention relates to a simulated oxygen-generating canister wherein a filter canister simulates in an open-flow system for training purposes, the oxygen generating chemical canister of the closed-flow, operational breathing apparatus. The invention also may be used as an operational system in its own right, under appropriate circumstances.
Emergency situations are best handled by personnel skilled in competent procedures that have been learned through experience and training. The best insurance is good, thorough preparation.
Many emergencies require that the responding personnel be provided breathing apparatus to cope with toxic environments. Fires, chemical leaks, explosive atmospheres and underground operations are obvious critical environments where breathing assistance is needed. In such cases the operator must have confidence in the apparatus and his own ability to operate it safely and effectively. Otherwise, his attention to the task at hand will suffer in the emergency.
For perfect realism, the oxygen breathing apparatus (OBA) itself would be used in training. But, inasmuch as OBA's use oxygen tanks and oxygen generating devices, cost becomes a significant factor when operational apparatus is employed for training.
Therefore, simulation is encouraged. The next best thing to the perfect realism of the apparatus itself is the apparatus, slightly modified for training. That is what the present invention provides, with an insignificant loss of realism.
Oxygen breathing apparatuses (OBA's) for the most part are one-way, closed loop systems which are not vented except by an exhaust valve. The oxygen canister or oxygen generator is removably inserted into a fitting on the OBA that channels the oxygen into inflatable bags from which the user can breath the oxygen on demand. The user's exhaled breath either is vented to the outside, or a portion of it is returned to the system for mixing with the oxygen supply. Outside air is excluded from the system, which is a practice that protects the user from breathing the toxic atmosphere if one is present. An example is the carbon monoxide filled environment that is created during a fire.
For training and other cases in which there is confidence that the only toxic fumes present in the environment are carbon monoxide with or without carbon dioxide, the present invention is appropriate in lieu of typical operational systems. The invention contemplates the modification or replication of the oxygen generating canister of the operational OBA, converting it into a flow-through system of filtering and chemically reactive layers. Together the layers are affective to remove particulates and react with the carbon dioxide in the incoming air to form calcium carbonate. Alteration also is made to the breathing bags such that the supply of breathable air is communicated by tubular conduit from the simulated generator to the user, and the user's exhaled breath is directed into the bags to provide the inflation the bags need for realism in feel and appearance. The conduit also is modified to include a cylinder as a permanent addition whereat carbon monoxide is converted to carbon dioxide.
The prior art includes U.S. Pat. No. 1,808,177 to Putter that discloses an air purifying appliance wherein pendulum breathing and valve-controlled breathing are combined. The pendulum filter may be of activated carbon, silica gel, or soda and lime. U.S. Pat. No. 4,297,117 to Holter et al discloses a fireproof respiratory face mask that has a granular expanded calcium aluminum silicate base coated with layers of soda lime, activated carbon dust, copper dust soaked in a caustic soda solution and manganese dioxide dust held between two layers of ceramic fiber fleece-like material felted together to hold the coated granules. U.S. Pat. No. 4,315,837 to Rourke et al discloses the use of the mixture of metallic oxides available as HOPCALITE from Mine Safety Applicances Corporation to its advantage as a catalyst for the decomposition of ozone, but to do so finely dividing its particles and adhering them to a support matrix for maximum effectiveness. U.S. Pat. No. 4,614,186 to John discloses an emergency breathing survival device having a clear plastic hood for the wearer that supports a cansister that is mounted on a mouthpiece and contains a carbon dioxide and water vapor absorbing material, usually consisting of silica gel pellets for removing water vapor and lithium hydroxide pellets for removing carbon dioxide. The mouthpiece directs inhaled air into the mouth, and directs exhaled air through the materials into the hood whereat it is available to the wearer during the emergency as his primary source of air. Some pellets that change color when exposed to moisture are intermingled with the material and are visible through a transparent side wall of the mouthpiece to indicate both before and during use whether the materials have lost their affectiveness. Another system to convert carbon dioxide to carbon monoxide has been developed by others that uses platinum as the active element. The surface area of the platinum is enhanced to maximize its catalytic affect by using it as a coating on porous ceramic pellets. As a catalyst in the system, the platinum does not deteriorate. However, it is part of the canister along with chemicals that are exhaustible. When the exhausted canister is discarded, the platinum is lost or must be removed and recycled.
The prior art in the OBA training field includes the operational equipment itself. It burns an oxygen candle as its source, or uses potassium superoxide to provide the oxygen by reacting with the moisture in the user's exhaled breath and at the same time removing the carbon dioxide from the breath. The user initiates operation of the oxygen-generating canister by pulling on a lanyard that is attached to a cotter pin which holds a spring-loaded striker plate in tension. Removal of the pin allows the plate to strike a shaft that extends into the canister. When struck, the shaft causes the oxygen generator to begin its production of oxygen. A device designed specifically for training is the training canister and system disclosed in U.S. Pat. No. 4,471,774. Starting with an operational OBA the system substitutes a flow-through filter in lieu of the oxygen generating canister, and a cross-over valve in lieu of the fitting into which the operational canister is inserted. The training canister also has an actuator that in appearance and operation is realistic to the trainee, but which is adapted internally to open a valve and allow air to flow through the filter and the cross-over valve to the user. The user's exhaled breath communicates through the other half of the cross-over valve into the bags and is used to inflate them. The bags themselves are not altered from their operational configuration; and, excess pressure is vented from the cross-over valve into the ambient atmosphere. Another prior art training device developed by others converts the tubing that is internal to the bags into a conduit from the canister to the fixture at the facemask. Again exhaled breath is used to inflate the bags. It is with such flow-through systems as the latter device that the invention disclosed herein is compatible.
The prior art fails to provide an apparatus for training that renders practical the use of catalytic platinum in terms of economy, and that can be used to faithfully create for the trainee a realistic experience in the use of an oxygen breathing apparatus in a smoke-filled environment that simulates the one the user can expect to encounter during the emergency for which the trainee is being prepared. The invention overcomes the failure of the prior art with an apparatus that also can be used in an encounter with an operational emergency in an environment where the toxic fumes are known to be limited to carbon monoxide and carbon dioxide. Accordingly, an object of the present invention is to provide a canister and oxygen breathing apparatus simulator to filter and convert the contaminants that are in the ambient atmosphere of the training or operational environment, such that the ambient atmosphere can be safely inhaled and used as the source of oxygen by the user of the canister and simulator. Such an environment or atmosphere is present in training devices whereat burners and smoke generators are employed to simulate emergency scenarios involving fire.